Virus-specific immunotherapy for transplant patients with primary immune deficiencies

A group from Baylor College of Medicine and Texas Children’s Cancer Center summarized the efficacy of treating viral infections with viral-specific T lymphocytes (VSTs) in patients with primary immunodeficiencies (PIDs). The group analyzed 36 patients who were treated with one or more VST infusions before or after undergoing hematopoietic stem cell transplantation (HSCT), and they found that complete or partial antiviral responses were seen in 86% of patients with CMV, 76% of patients with EBV and all patients with adenovirus or HHV-6. There were no associated complications.

Viral reactivation after HSCT can, in some cases, lead to life-threatening complications, and individuals with PIDs are at an even greater risk of developing viremia due to the absence of T cell activity against infections (Wehr 2015). The use of immunosuppressive medications further increases the chance of reactivation post-transplant (Inazawa 2015). As VST infusions have been successful in treating HSCT patients (Leen 2013), the Baylor group was interested in investigating their success in treating this subgroup.

The study found an overall survival rate of 80% among treated patients. Although it was not possible to compare the patients to any control group, preliminary results showed VST therapy to be a safe and effective treatment option for patients with PIDs who undergo HSCT. Although the availability of this therapy is currently very limited due to the costs and the difficulty of production, new protocols have reduced the barriers to production. The authors hope to see a Phase II trial of VST therapy for PIDs in the future.

Viracyte, a company that was spun off out of this research, is building banks of donor cells to treat patients with drug resistant viruses. They have three clinical trials in progress, but this effort is still many years away from possible FDA approval.

Tessa Therapeutics was granted “Fast Track” designation for EBV specific T lymphocyte therapy for EBV related head and neck cancers in 2015, and a Phase III trial is in progress. Also, Atara Bio has licensed the rights to market cytotoxic T cells from Memorial Sloan Kettering Cancer Center; Phase II studies are in progress for EBV and CMV specific immunotherapy.

For more information, read the full paper (Naik 2016).